夏季南极长城湾海流变化特征及其对浮游植物生物量的影响

通过对2010/2011年夏季南极长城湾叶绿素a浓度和海流等环境参数的传感器连续观测；研究其时空变化特征及海流对浮游植物生物量的影响。结果表明；12.9 m水层叶绿素a浓度从12月中旬开始增长；直至2月上旬开始维持相对稳定；期间出现两个高值点（2.74 μg/L和3.76 μg/L）。叶绿素a浓度表现出了24 h周期变化特征；每日叶绿素a浓度最高值出现在正午前后时段的概率要高于其他时段。表层海水受西北风影响；流速较大；约为60~100 cm/s；中层和底层水体流速较小；约为10 cm/s。表层的风海流使海水在长城湾发生辐散；下层海水向上涌升；驱动了水体的垂直交换。长城湾与麦克斯韦尔湾存在水体交换；水体主要从中层进入湾内；从表层输出。长城湾的叶绿素a浓度与流速呈显著负相关；表明低流速环境有利于长城湾浮游植物的生长。

Effects of current velocity on phytoplankton biomass in Great Wall Bay, Antarctica during summer 2010/2011

Understanding the mechanism by which environmental factors affects phytoplankton growth in summer is essential for determining polar marine ecosystem responses to global climate change. Here we deployed an online mooring system in Great Wall Bay to determine how current velocity and local physical forcing affect the temporal and spatial distribution of phytoplankton biomass in Antarctic coastal waters. The results show that chlorophyll a(Chl a)concentrations accumulated from mid-December and two significant blooms developed in January (2.74 μg/L and 3.76 μg/L) and were then maintained at a relatively high level. The diurnal variations of cholorophyll a concentrations were observed in both upper and middle layers during the monitoring period. The surface current velocity reached approximately (60-100)cm/s, while the middle and bottom current velocity was limited to about 10 cm/s. We conclude that summer winds played an important role in the surface current velocity and direction. The monitoring site appears to exchange with adjacent oceanic waters, such an intrusion of water would bring in varied phytoplankton species. The results of Pearson correlation analysis showed the significant and positive influence of low current velocity on chlorophyll a concentrations, especially during phytoplankton blooms, whereas the increased current velocity showed the significant and negative correlations with phytoplankton biomass.